Optical detection of electron paramagnetic resonance for intrinsic defects produced in ZnO by 2.5-MeV electron irradiationin situat 4.2 K

Intrinsic defects produced in ZnO by 2.5-MeV electron irradiation in situ at 4.2 K are studied by optical detection of electron paramagnetic resonance (ODEPR). Observed in the photoluminescence (PL) are ODEPR signals, which are identified with the oxygen vacancy, VO⁺, interstitial zinc, Znᵢ⁺, and zinc-vacancy--zinc-interstitial Frenkel pairs. The Frenkel pairs are primarily observed in their $S=1$ exchange-coupled state, supplying strong evidence that interstitial zinc is a shallow effective mass double donor in ZnO. Annealing stages at ~65--1190.3em0exK and ~145--1700.3em0exK are observed for the defects associated with the zinc sublattice and are identified with the migration of interstitial zinc. Although interstitial oxygen is not observed in the ODEPR, a higher-temperature annealing stage observed in the PL at ~160--2300.3em0exK is tentatively identified with the onset of its migration. The oxygen vacancy is stable to ~4000.2em0ex^∘C. The relationship between the spin-dependent processes producing the ODEPR signals and the PL of the material remains unclear.